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Cohort profile
Cohort profile: Research on Obesity and Diabetes among African Migrants in Europe and Africa Prospective (RODAM-Pros) cohort study
  1. Charles Agyemang1,
  2. Eva L van der Linden1,2,
  3. Daniel Antwi-Berko1,
  4. Samuel Nkansah Darko3,4,
  5. Sampson Twumasi-Ankrah3,5,
  6. Karlijn Meeks1,6,
  7. Bert-Jan H van den Born1,2,
  8. Peter Henneman7,
  9. Ellis Owusu-Dabo3,
  10. Erik Beune1
  1. 1Department of Public and Occupational Health, Amsterdam UMC, University of Amsterdam, Amsterdam Public Health Research Institute, Amsterdam, The Netherlands
  2. 2Department of Vascular Medicine, Amsterdam UMC, University of Amsterdam, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands
  3. 3School of Public Health, Kwame Nkrumah University of Science and Technology (KNUST), Kumasi, Ghana
  4. 4Department of Molecular Medicine, Kwame Nkrumah University of Science and Technology (KNUST), Kumasi, Ghana
  5. 5Department of Statistics and Actuarial Science, Kwame Nkrumah University of Science and Technology (KNUST), Kumasi, Ghana
  6. 6Center for Research on Genomics and Global Health, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, USA
  7. 7Department of Human Genetics, Genome Diagnostics laboratory Amsterdam, Reproduction & Development, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
  1. Correspondence to Dr Charles Agyemang; c.o.agyemang{at}amsterdamumc.nl

Abstract

Purpose The Research on Obesity and Diabetes among African Migrants (RODAM) prospective (RODAM-Pros) cohort study was established to identify key changes in environmental exposures and epigenetic modifications driving the high burden of cardiovascular disease (CVD) risk among sub-Saharan African migrants.

Participants All the participants in the RODAM cross-sectional study that completed the baseline assessment (n=5114) were eligible for the follow-up of which 2165 participants (n=638 from rural-Ghana, n=608 from urban-Ghana, and n=919 Ghanaian migrants in Amsterdam, the Netherlands) were included in the RODAM-Pros cohort study. Additionally, we included a subsample of European-Dutch (n=2098) to enable a comparison to be made between Ghanaian migrants living in the Netherlands and the European-Dutch host population.

Findings to date Follow-up data have been collected on demographics, socioeconomic status, medical history, psychosocial environment, lifestyle factors, nutrition, anthropometrics, blood pressure, fasting blood, urine and stool samples. Biochemical analyses included glucose metabolism, lipid profile, electrolytes and renal function, liver metabolism and inflammation. In a subsample, we assessed DNA methylation patterns using Infinium 850K DNA Methylation BeadChip. Baseline results indicated that migrants have higher prevalence of CVD risk factors than non-migrants. Epigenome-wide association studies suggest important differences in DNA methylation between migrants and non-migrants. The follow-up study will shed further light on key-specific environmental exposures and epigenetic modifications contributing to the high burden of CVD risk among sub-Saharan African migrants.

Future plans Follow-up is planned at 5-year intervals, baseline completed in 2015 and first follow-up completed in 2021.

  • Hypertension
  • EPIDEMIOLOGY
  • PUBLIC HEALTH
  • STATISTICS & RESEARCH METHODS
  • VASCULAR MEDICINE
  • DIABETES & ENDOCRINOLOGY

Data availability statement

Data are available on reasonable request. These requests can be made to de RODAM-Pros cohort coordinator Dr Erik Beune (e.j.beune@amsterdamumc.nl) or principal investigator, CA (c.o.agyemang@amsterdamumc.nl).

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STRENGTHS AND LIMITATIONS OF THIS STUDY

  • The main strength of the Research on Obesity and Diabetes among African Migrants prospective (RODAM-Pros) cohort study is the longitudinal cohort design, including representative samples of Ghanaian migrants and their non-migrant compatriots of predominantly Akan ethnicity living in their country of origin, alongside a sample of the host European population, which is unique.

  • The RODAM-Pros cohort study uses well-standardised approaches across the study sites in rural Ghana, urban Ghana and Amsterdam, the Netherlands, and has collected a variety of data on demographics, socioeconomic status, psychosocial environment, lifestyle, nutrition, biological factors and epigenetics.

  • This cohort may be limited by a relatively low response rates, especially in urban Ghana, due to the COVID-19 pandemic, but the response rates achieved will give insight into the drivers of the high burden of cardiovascular disease and its risk factors among these populations.

Introduction

Cardiovascular disease (CVD) is the main cause of death in the European Union (EU) accounting for 1.9 million deaths yearly in the EU, equivalent to 40% of all deaths each year in this region.1 CVD is also a major health problem confronting migrant and ethnic minorities in Europe, and the rate of CVD incidence and mortality are higher among these populations than in the European host populations.2–4 This inevitably contributes importantly to the widening health inequalities between migrants and ethnic minorities and the European host populations. Sub-Saharan Africa (SSA) migrants, especially West-Africans, have been particularly affected by stroke, being 1.5–2.5 times more common in these groups than in the European host populations.2–5 SSA patients with hypertension are also at greater risk of developing cardiovascular complications, such as renal disease, than other populations.2 6

Hypertension, the single most important modifiable risk factor for CVD, is consistently highly prevalent among SSA origin populations and appears to be a major contributor to their elevated stroke risk.7–9 Hypertension prevalence in West-African migrants, for example, is 1.5–3.5 times higher than in the European host population.10 The Healthy Life in an Urban Setting (HELIUS) study in Amsterdam, the Netherlands, has shown that the prevalence of hypertension was 62% and 52% in Ghanaian migrant men and women, respectively, compared with 34% and 19% in their European Dutch counterparts.10 Similarly, the prevalence of type 2 diabetes is higher in SSA migrants than in the European host population.11 A meta-analysis of papers published between 1994 and 2014 in Europe showed that the pooled odds ratio of type 2 diabetes was about 2.5-fold higher in SSA migrants than in the European host population.12 Moreover, overweight and obesity, too, have been shown to be more prevalent among SSA migrants compared with individuals of European descent, especially in women.12 These huge disparities in prevalence of CVDs risk factors, and related complications between SSA migrants and the European host population has led to the burning question: which factors are driving the increased burden of CVD and its risk factors among SSA migrants?

At present, the underlying reasons for the increased risk of CVD risk factors among SSA migrants are incompletely understood. Lack of understanding of the drivers of increased CVD risk in SSA migrants prohibits the development of strategies that can mitigate existing differences in CVD outcomes. This is happening at a time when preventive measures have led to reduction in CVDs and their risk factors in the European general populations for the last few decades.1 More evidence on the underlying factors is clearly needed in order to develop adequate policy, clinical and public health responses to minimise the high burden of CVD risk factors and related complications among these populations.13

Notwithstanding, several factors have been proposed as the underlying drivers for the high burden of CVD risk factors among SSA migrants, including migration-related lifestyle changes, psychosocial stress and low socioeconomic status, genetic susceptibility and gene–environment interactions, however, the key specific modifiable risk factors within these broad categories still remain to be determined.14 Additionally, at the moment, very few genetic variants have been identified to directly influence CVD risk, but, analyses of several common polymorphisms associated with underlying mechanisms, for example, salt sensitivity and heat stress, indicate that these polygenic traits might influence the tendency to develop CVD risk factors such as hypertension and diabetes.15 Additionally, epigenetic alterations might also influence the risk of CVD among migrant populations.16 Furthermore, the disparities in CVD risk may be affected by differences in the gut microbiome.17 However, the current limited available knowledge is mainly based on cross-sectional analyses. Answering the critical question of what are causing the high burden of CVDs and their risk factors in SSA migrants requires a longitudinal design. The Research on Obesity and Diabetes among African Migrants (RODAM) prospective (RODAM-Pros) cohort study was, therefore, set up to identify key changes in environmental exposures (eg, socioeconomic status, lifestyle factors, psychosocial factors), biological factors and epigenetic modifications in the development of CVD risk factors among SSA migrants and their non-migrant peers living in SSA. Through the RODAM-Pros cohort study, we aim to provide better understanding of the factors driving the high rates of CVD risk factors among SSA migrants, and provide a knowledge base to improve diagnosis and treatment of CVD risk factors in this population.

Cohort description

This cohort profile describes the RODAM-Pros cohort study based on the RODAM study. The RODAM study was conducted between 2012 and 2015 and was based on a well-defined homogenous SSA population (ie, Ghanaian migrants of mostly Akan ancestral heritage) living in three European cities (Amsterdam, the Netherlands; Berlin, Germany and London, UK) and their compatriots living in rural and urban Akan region of Ghana.18 The follow-up of the RODAM-Pros cohort conducted between 2019 and 2021 is restricted to the Netherlands, rural and urban Ghana because the recruitment strategies in these sites allowed the study participants to be followed over time. In addition, we included participants of Ghanaian ethnicity and European-Dutch from the HELIUS study, who were not initially included in the RODAM study, to maximise the sample size and to allow comparison of migrants with the European host population. The HELIUS study is a multiethnic prospective cohort study on health and healthcare utilisation among ethnic groups in Europe. The RODAM and the HELIUS studies used exactly the same sampling, recruitment and data collection methods at baseline and follow-up. The rationale and study design of the RODAM study18 and HELIUS study19 has been published before.

Baseline recruitment strategy in Ghana and the Netherlands (2012–2015)

At baseline, 15 villages in the Ashanti region and two cities (Kumasi and Obuasi) in Ghana served as the rural and urban recruitment sites using the list of enumeration areas (EAs) in the Ashanti region from the 2010 census as the initial sampling frame.18 We used a multistage sampling procedure to arrive at the sampling of 30 EAs consisting of 15 rural EAs and 15 urban (Kumasi and Obuasi) EAs. These were selected from over 2000 urban EAs and 1000 rural EAs following the stratification and weighting of the EAs. The health and community authorities in all the selected EAs were informed by letters about the study. The RODAM team organised mini clinics in the various communities for a period of 1–2 weeks for data collection.

In the Netherlands, Ghanaian participants were randomly drawn from the Amsterdam Municipal register, which contains data on country of birth of each citizen and their parents. The Ghanaian participants identified from the register aged ≥25–70 years were sent an invitation letter combined with study information and an opt-out response card. An appointment for physical examination was made for those that agreed to participate in the study. In addition, participants completed questionnaires through face-to-face interviews by research assistants or independently by filling out the paper version or online version of the questionnaire depending on the preference of the participants. The participants were asked to consent for future follow-up, planned to be conducted every 5 years, and for their data to be linked to the national registry data on health outcomes and healthcare at the individual level to study changes in diseases experiences over time.

Patient and public involvement

The RODAM study engaged the Ghanaian community in both Europe and Ghana by working with religious communities and endorsement from local community leaders for the recruitment of the study participants and the dissemination of the study results. We also provided information about the study via local Ghanaian community organisations and local media via Ghanaian radio and television stations.

Follow-up recruitment strategy (2019–2021)

In Ghana, all participants contact details including house address, mobile numbers and next-of-kin contact details were compiled at baseline. In the follow-up, the study participants were contacted by phone in urban Ghana (n=1452) and by home visits in rural Ghana (n=1111). If there were no means of contact available for a participant (e.g., because of changed phone numbers), then we relied on households head’s contact details or the community members in each specific EA to reach the participant. If a potential participant had moved to another village or a city, effort was made to reach them through the participant’s contact details.

In Amsterdam, the Netherlands, all Ghanaian participants who participated in the baseline RODAM study assessment and agreed to be approached for future studies (n=1504) were invited for follow-up examination. As the RODAM and the HELIUS studies used exactly the same methods at baseline and follow-up, we included Ghanaian participants in the HELIUS study (n=1047) to enlarge the RODAM-Pros cohort sample in Amsterdam. Furthermore, we included a subpopulation of HELIUS study participants of European-Dutch origin (n=2098) to enable comparison to be made between the Ghanaian migrants in the Netherlands with the host European Dutch population. Effort was made to increase the response rate by means of repeated phone calls by the research team if individuals did not respond to the initial invitation. Furthermore, community sensitisations were carried out through radio, television and community organisations such as churches and African mosques to create awareness about the importance of participating in the follow-up. In Ghana, the research team visited several houses in both rural and urban Ghana to motivate participants to take part in the study.

Follow-up data collection

Table 1 summarises the data collected from participants at baseline and follow-up assessment. In both the Netherlands and in Ghana, all the participants that agreed to participate were invited for physical examination and to complete a questionnaire at the local research clinic or health centre. The study and procedures involved were explained to each participant by trained research assistants and informed consent was signed for participation, storage of biological materials in Biobank and to be approached for future (sub) studies. Participants were asked to fast 8–12 hours before their physical measurement.

Table 1

Summary of physical and biological examination variables measured at baseline and follow-up

Physical measurements

Physical measurements were carried out using validated devices according to standardised operational procedures (SOPs). Physical measurements included anthropometric indices (weight, height, waist circumference and hip circumference) and blood pressure (table 1). Height was measured using a portable stadiometer SECA 217; weight was measured with SECA 877 wearing light clothing and no shoes. Abdominal and hip circumference were measured with a measuring tape, at the point midway between the iliac crest and the costal margin, and over the trochanter major of the femur, respectively. All anthropometric measurements were taken twice. Blood pressure was measured three times with a validated semiautomated device (The Microlife WatchBP home) in a sitting position after at least 5 min rest, with appropriate cuffs around the left upper arm. In a subsample (n=55) of participants with newly detected, untreated hypertension during their study visit, 24 hours ambulatory blood pressure measurement was performed with a validated device (Spacelabs 90207/90217).

Questionnaire

After the physical examination, the participants completed a structured health questionnaire containing questions on demographics, socioeconomic status, migration-related factors, psychosocial vulnerability (perceived discrimination, social support, mastery, recent negative life events and current depression), health status and behaviour (self-reported general health and presence and history of diseases, family history of diseases, dietary behaviour, physical activity, alcohol and smoking, and adherence to medications) by using appropriate validated instruments where necessary (table 2) by trained and ethnically matched interviewers. The questionnaires were conducted face to face by trained interviewers of Ghanaian background in the preferred language of the participant either in English, Dutch or a Ghanaian language and lasted for about 75 min. The European-Dutch participants completed an online digital shortened Dutch version of the structured health questionnaire.

Table 2

Summary of variables collected at baseline and follow-up by a questionnaire

Biological material

Blood samples

Fasting venous blood samples were collected by trained research assistants in the Netherlands and Ghana. Blood samples were manually processed and aliquoted immediately after collection by a trained technician according to SOPs, and then temporarily stored at 4°C–7°C at the local research location. The SOPs in both the Netherlands and Ghana were strictly followed to ensure that the samples were collected, handled, processed, transported and stored in the same way in both countries. The samples, including EDTA whole blood, PAX-gene blood and heparin plasma, were then transported to the local laboratories in Kwame Nkrumah University of Science and Technology, Kumasi, and Amsterdam University Medical Centres (UMC), Amsterdam, where samples were checked, registered and stored at −80°C.

Morning urine sample

All the study participants were asked to bring early morning, midstream, urine samples in a clean jar. In addition, 24-hour urine samples were collected in a subsample of the study population (n=408).

Stool sample

The study participants were asked to bring fresh stool samples in a stool tube as has been provided by the research team. These samples were transported to the respective local laboratory and stored at −80°C.

Transfer of biological material for biochemical analyses and genotyping

All the samples in Ghana were shipped to Amsterdam, the Netherlands, in CXR500 dry shippers including an activated temperature logger with intervals of 30 min, filled with liquid nitrogen, to keep the samples frozen at −80°C. The staff involved with the shipment of the samples were trained in the preparation and filling of dryshippers and on legal and regulatory aspects of shipment of samples such as Material Transfer Agreement in order to minimise factors that might affect the integrity of the samples such as temperature, packaging, import/export requirements, seasons and transit time/ship days. We maintained a shipment log to record the receipt and dissemination of shipments; and each shipment entry was given a unique shipment number.

All the blood, urine and stool samples were transported to Amsterdam UMC Biobank and parts of the samples were processed for biochemical analyses at the Central Biochemical Laboratory of the Amsterdam UMC. All biochemical analyses were performed in the same laboratory in Amsterdam, to prevent bias of interlaboratory differences. Biochemical analysis of blood included glucose metabolism (fasting glucose, hemoglobine A1c), lipid profile (total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol and triglycerides), renal function (creatinine), liver metabolism (alanine transaminase, aspartate aminotransferase and γ-glutamyl transpeptidase) and inflammation (high-sensitivity C reactive protein). Urine samples were analysed for renal function and electrolytes (albumin, creatinine, sodium, potassium and urea). Stool samples will be analysed to evaluate the role of microbiome and its impact on CVD risk factors among migrants.

Each participant received a summary of their main results accompanied by an explanation and recommendation to contact his/her general practitioner if the results were abnormal.

Deceased participants

For RODAM participants who died in the period between baseline and follow-up data collection, efforts were made to retrieve information on causes of death. In the Netherlands, at baseline, participants gave informed consent to link up their information to the national statistics registration (Centraal Bureau voor de Statistiek) data on cause and date of death—based on medical certification of death, using the International Classification of Disease (ICD) version 10 classification. In Ghana, no reliable vital national registration system on cause of death exists. Therefore, information on causes of death of the deceased participants was collected using a validated verbal autopsy instrument. During verbal autopsy interviews with families, information about the events leading to death was collected, using the shortened Verbal Autopsy Instrument developed by the Population Health Metrics Research Consortium, based on the WHO standards.20 This Verbal Autopsy Instrument was then analysed using the SmartVA software (https://www.healthdata.org/verbal-autopsy/tools), resulting in most likely cause of death, classified based on the ICD-10.21

Epigenetics

We included around 1300 participants in the epigenetic studies. A core interest was to identify key epigenetic modifications driving the high burden of hypertension among African migrants. In a nested case–control study, including 793 participants (n=174 rural Ghana, n=161 urban Ghana, n=145 Amsterdam Ghanaians and n=313 Dutch) an epigenome-wide association study (EWAS) were be conducted to assess differentially methylated positions and regions associated with incident hypertension at follow-up. These participants were selected based on their hypertension status at baseline (normotensive) and at follow-up (either normotensive control or hypertensive case). An additional 507 participants (n=169 rural Ghana, n=169 urban Ghana and n=169 Amsterdam Ghanaians) were randomly selected to study DNA methylation loci associated with (other) CVD risk factors. DNA was isolated from whole blood at the Core Facility Genomics of the Amsterdam UMC. DNA samples were sent to Erasmus University, Rotterdam for DNA methylation profiling using Infinium Methylation EPIC BeadChip of Illumina (850K). Raw methylation data were sent to Amsterdam UMC for quality control and data analysis. mRNA will be isolated from whole blood (PAXgene stored). mRNA expression analysis will be performed in a subset of randomly selected cases and controls using RNA sequencing (RNA-seq) depending on the results of the epigenetic analyses.

Findings to date

The follow-up data collection of the RODAM-Pros cohort study in rural and urban Ghana, and the Netherlands completed in October 2021. The mean time to follow-up was 6.4 years, with a range of 3.6–9.9 years. The response rates were 63.3% in rural Ghana, 43.9% in urban Ghana, 68.4% among Ghanaian migrants and 92.6% among European-Dutch. Of the respondents, 90.8% of rural Ghanaian, 95.3% of urban Ghanaian, 52.7% of Amsterdam Ghanaian and 67.2% of European-Dutch participants completed the physical examination (figure 1). The response rate was affected by the COVID-19 pandemic, which started in the middle of the data collection. Following the outbreak, data collection was interrupted several times in both Ghana and the Netherlands because of the COVID-19 shutdowns. In urban Ghana, especially in Obuasi, several participants relocated to their hometowns due to COVID-19 shutdown and many were not traceable despite efforts to reach them. We carried out non-response analyses to assess the characteristics of the individuals who participated and those who did not participate in the follow-up. Among rural and urban Ghanaians, there were no differences in sex and educational levels between respondents and non-respondents, but respondents were less frequently living in urban Ghana than in rural Ghana (table 3). Respondents were more frequently employed than non-respondents. Among Ghanaian migrants in the Netherlands, there was no differences in sex, region of origin and educational level between respondents and non-respondents; but the respondents were older, had been residing in Amsterdam for longer, and were more frequently employed than their non-respondent peers (table 3). Among the European-Dutch, the respondents were frequently males, older, had higher educational level, and were more frequently employed than non-respondents.

Table 3

Baseline characteristics of non-respondents and respondents in follow-up data collection, for Ghana, Amsterdam Ghanaians and Dutch

Figure 1

Response and participation rates. RODAM, Research on Obesity and Diabetes among African Migrants.

The RODAM baseline data have shed light on the high burden of CVD risk factors such as obesity, type 2 diabetes, hypertension and dyslipidaemia among Ghanaian migrants and their non-migrant Ghanaian compatriots living in rural and urban Ghana.22 For example, the prevalence ratio of obesity was five times higher in urban Ghanaian men and 11–15 fold higher among Ghanaian migrant men living in the various European countries compared with their rural Ghanaian men counterparts.22 The baseline data of the RODAM-Pros cohort also show that despite the high burden of CVD risk factors among Ghanaian migrants, they have lower rates of microvascular and macrovascular complications as compared with non-migrant Ghanaians.23 24 The RODAM study has identified various cross-sectional factors associated with CVD risk factors.25–27 In addition, the study has resulted in the first EWAS for type 2 diabetes in SSA, in which we identified several CpG sites that were differentially methylated between type 2 diabetes cases and controls at an epigenome-wide level.28 In our study of epigenome-wide DNA methylation differences between migrant and non-migrant Ghanaians, we identified 13 differentially methylated positions and 3 differentially methylated regions between migrants and non-migrants, with DNA methylation differences ranging from 0.1 to 4.5%.29 The complete list of publications based on the baseline RODAM study data is available online in the RODAM study website (http://www.rod-am.eu/publications/).

The RODAM-Pros longitudinal cohort will shed further light on the key specific causal factors including lifestyle, psychosocial stressors, socioeconomic circumstances, physiological changes and epigenetic modifications among many factors that are driving the high burden of CVD and its risk factors in SSA migrants and their compatriots living in rural and urban SSA.

Strengths and limitations

The main strength of the RODAM-Pros cohort is the uniqueness of a longitudinal cohort of Ghanaian migrants and their non-migrant compatriots of predominantly Akan ethnicity living in their country of origin, alongside a cohort of the host European population. Another strength of the RODAM-Pros cohort is the use of well-standardised methods across the study sites in rural Ghana, urban Ghana and Amsterdam, the Netherlands. A further strength of the RODAM-Pros cohort is the large sample size and detailed characterisation of the study participants including data on demographics, socioeconomic status, psychosocial environment, lifestyle, nutrition, biochemical characterisation and epigenetics.

There are also limitations to the RODAM-Pros cohort. First, although the data collection was highly standardised across all sites, the recruitment strategies were adapted to suit the local circumstances due to differences in registration systems. In the Netherlands, the Ghanaian migrants and the European-Dutch participants were drawn from the Amsterdam Municipal population register, whereas Ghanaian participants living in Ghana were drawn from the list of EAs. It is possible that individuals who are not included in the register, such as non-documented migrants, differ in terms of demographics and socioeconomic status, which might somewhat affect the representativeness of Ghanaian migrants in Amsterdam, the Netherlands. Another limitation is the relatively low response due to impact of COVID-19 pandemic. The COVID-19 pandemic lockdowns deterred some participants to participate in the follow-up because of fear of infection, especially in urban Ghana, where the entire data collection occurred within the pandemic period. In a non-response analysis, there were no differences in sex and educational levels between respondents and non-respondents; but non-respondents were more frequently living in urban Ghana than in rural Ghana, which might somewhat bias the results. Another limitation is the use of self-reported data through questionnaires such as WHO/Rose questionnaire, WHO GPAQ V.2 and Ghana-specific Food Propensity Questionnaire, which may be subject to response bias. Additionally, bias could have been introduced as questionnaires were completed during an interview rather than by self-completion. To limit this bias, interviewers were trained to conduct the interview in a structured and objective manner. Despite these potential limitations, this unique RODAM-Pros longitudinal cohort study offers an important opportunity to gain insight into the drivers of the high burden of CVDs and their risk factors among SSA migrants.

Collaboration

We welcome potential collaboration with other researchers especially on epigenetics studies. Researchers can visit the RODAM-Pros cohort website (http://www.rod-am.eu/follow-up/about/) for more information about the study.

Data availability statement

Data are available on reasonable request. These requests can be made to de RODAM-Pros cohort coordinator Dr Erik Beune (e.j.beune@amsterdamumc.nl) or principal investigator, CA (c.o.agyemang@amsterdamumc.nl).

Ethics statements

Patient consent for publication

Ethics approval

Ethical approval of the study protocols was obtained from the respective ethics committees in Ghana (School of Medical Sciences/Komfo Anokye Teaching Hospital Committee on Human Research, Publication & Ethical Review Board, reference CHRPE/AP/172/19), and the Netherlands (Institutional Review Board of the AMC, University of Amsterdam, reference NL32251.018.10). Participants gave informed consent to participate in the study before taking part.

Acknowledgments

We thank the research assistants, interviewers and other staff of the three research locations who have taken part in gathering the data and, most of all, the Ghanaian volunteers participating in this project. We gratefully acknowledge Amsterdam UMC, AMC-Biobank for their support in biobank management and high-quality storage of collected samples.

References

Footnotes

  • Contributors CA, EB, ELvdL, PH, B-JHvdB and EO-D established the cohort and provided intellectual inputs to the manuscript. CA, ELvdL and EB conceived the present manuscript, CA and ELvdL drafted the manuscript, and ELvdL conducted the data analysis. DA-B, SND, ST-A, KM, B-JHvdB, PH and EO-D critically revised the manuscript. CA, ELvdL and EB prepared the final version for the submission. All authors reviewed and approved the final version of the manuscript. CA had full responsibility for the work and the conduct of the study, had access to the data, and controlled the decision to publish.

  • Funding The study was funded by grants from the European Research Council (Grant number 772244).

  • Competing interests None declared.

  • Patient and public involvement Patients and/or the public were involved in the design, or conduct, or reporting, or dissemination plans of this research. Refer to the Methods section for further details.

  • Provenance and peer review Not commissioned; externally peer reviewed.